NL2034521A - Solar cell and photovoltaic module - Google Patents
Solar cell and photovoltaic module Download PDFInfo
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- NL2034521A NL2034521A NL2034521A NL2034521A NL2034521A NL 2034521 A NL2034521 A NL 2034521A NL 2034521 A NL2034521 A NL 2034521A NL 2034521 A NL2034521 A NL 2034521A NL 2034521 A NL2034521 A NL 2034521A
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/048—Encapsulation of modules
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022433—Particular geometry of the grid contacts
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
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- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0352—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
- H01L31/035272—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions characterised by at least one potential jump barrier or surface barrier
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- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/042—PV modules or arrays of single PV cells
- H01L31/05—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells
- H01L31/0504—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module
- H01L31/0516—Electrical interconnection means between PV cells inside the PV module, e.g. series connection of PV cells specially adapted for series or parallel connection of solar cells in a module specially adapted for interconnection of back-contact solar cells
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- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
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- H01L31/04—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices
- H01L31/06—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers
- H01L31/072—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type
- H01L31/0745—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof adapted as photovoltaic [PV] conversion devices characterised by potential barriers the potential barriers being only of the PN heterojunction type comprising a AIVBIV heterojunction, e.g. Si/Ge, SiGe/Si or Si/SiC solar cells
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Abstract
The embodiments of the present application relate to the technical field of solar cells, in particular to a solar cell and a photovoltaic module. The solar cell includes a substrate having 5 a front surface and a rear surface opposite to the front surface, where the front surface includes a metal pattern region and a non metal pattern region. The solar cell further includes a first tunneling layer and a first doped conductive layer arranged on the metal pattern region of the front surface of the substrate and arranged in sequence in a direction away from the front surface of the substrate, where the first doped conductive layer has a same type of doping lO elements as the substrate. The solar cell further includes a second tunneling layer and a second doped conductive layer arranged on the rear surface of the substrate and arranged in sequence in a direction away from the rear surface of the substrate, where the second doped conductive layer has different type of doping elements from the first doped conductive layer, the first doped conductive layer has a greater concentration of activated doping elements than the second 15 doped conductive layer, and a thickness of the first doped conductive layer has is not greater than a thickness of the second doped conductive layer. The embodiments of the application are conducive to improving the photoelectric conversion performance of the solar cell. (FIG.1) 26
Description
SOLAR CELL AND PHOTOVOLTAIC MODULE
[0001] Embodiments of the present application relate to the field of solar cells, and in particular to a solar cell and a photovoltaic module.
[0002] A solar cell has desirable photoelectric conversion capability. Generally, a tunneling oxide layer and a doped conductive layer are prepared on a surface of a substrate surface to suppress carrier recombination on the surface of the substrate and enhance the passivation effect on the substrate. The doped conductive layer has doping elements.
[0003] The doped conductive layer is configured to achieve field passivation. Doping elements concentration in the doped conductive layer plays an important role in the passivation effect of the doped conductive layer, thus affecting the photoelectric conversion performance of the solar cell. However, at present, the solar cell has the problem of low photoelectric conversion efficiency.
[0004] Embodiments of the present application provide a solar cell and a photovoltaic module, which are at least beneficial for improving the photoelectric conversion efficiency of the solar cell.
[0005] The embodiment of the present application provides a solar cell photovoltaic module, which is at least conducive to improving the photoelectric conversion efficiency of the solar cell.
[0006] A solar cell is provided according to the embodiments of the present application, the solar cell includes a substrate having a front surface and a rear surface opposite to the front surface, where the front surface includes a metal pattern region and a non metal pattern region; a first tunneling layer and a first doped conductive layer arranged on the metal pattern region of the front surface of the substrate and arranged in sequence in a direction away from the front surface of the substrate. The first doped conductive layer has a same type of doping elements as the substrate. The solar cell further includes a second tunneling layer and a second doped 1 conductive layer arranged on the rear surface of the substrate and arranged in sequence in a direction away from the rear surface of the substrate. The second doped conductive layer has different type of doping elements from the first doped conductive layer, the first doped conductive layer has a greater concentration of activated doping elements than the second doped conductive layer, and a thickness of the thickness of the first doped conductive layer is not greater than a thickness of the second doped conductive layer.
[0007] In some embodiments, the first doped conductive layer has a thickness of 20 nm to 300 nm, and the second doped conductive layer has a thickness of 50 nm to 500 nm.
[0008] In some embodiments, the first doped conductive layer includes a first doping element, the first doping element is activated by annealing to obtain an activated first doping element, and an activation rate of the first doping element in the first doped conductive layer ranges from 40% to 80%.
[0009] In some embodiments, the concentration of the activated first doping element ranges from 1x10%%atom/cm’ to 6x10*atom/cm’.
[0010] In some embodiments, a ratio of a width of the first doped conductive layer to a width of the substrate ranges from 0.0001 to 0.0012.
[0011] In some embodiments, the width of the first doped conductive layer ranges from 20pm to 200um.
[0012] In some embodiments, an area ratio of the first doped conductive layer to the front surface of the substrate ranges from 0.01 to 0.15.
[0013] In some embodiments, the second doped conductive layer includes a second doping element, the second doping element is activated by annealing to obtain an activated second doping element, and an activation rate of the second doping element in the second doped conductive layer ranges from 30% to 80%.
[0014] In some embodiments, the activated doping element concentration of the second doping element ranges from 4x10" atom/cm® to 9x10" atom/cm’.
[0015] In some embodiments, the second doped conductive layer includes a first region and a second region, the second region 1s defined close to the substrate; in a direction from the first region to the second region, a slope of a doping curve of the activated second doping element in the first region is not less than 0, a slope of the doping curve of the activated second doping element in the second region is less than 0, and the slope of the doping curve shows that the activated doping element concentration of the second doping element changes with a doping depth. 2
[0016] In some embodiments, the slope of the doping curve of the activated second doping element in the first region ranges from 1xE!6 to IxE°, the slope of the doping curve of the activated second doping element in the second region ranges from -1xE!° to -1xE2°.
[0017] In some embodiments, the activated doping element concentration of the second doping element in the first region ranges from 4x10" atom/cm® to 9x10'atom/cm’, the activated doping element concentration of the second doping element in the second region ranges from 1x10'atom/cm® to 9x10" atom/cm®.
[0018] In some embodiments, the second doped conductive layer has a thickness of 50 nm to 500 nm in the first region, and the second doped conductive layer has a thickness of 30 nm
I0 to 300 nm in the second region.
[0019] In some embodiments, the substrate is an N-type substrate, the first doped conductive layer is an N-type doped conductive layer, and the second doped conductive layer is a P-type doped conductive layer.
[0020] In some embodiments, doping elements of the first doped conductive layer are phosphorus elements, and doping elements of the second doped conductive layer are boron elements.
[0021] In some embodiments, materials of the first doped conductive layer and the second doped conductive layer include at least one of amorphous silicon, microcrystalline silicon or polycrystalline silicon.
[0022] In some embodiments, the solar cell further includes a first passivation layer, where a first part of the first passivation layer is arranged on a surface of the first doped conductive layer away from the substrate, and a second part of the first passivation layer is arranged on the non metal pattern region of the front surface of the substrate.
[0023] In some embodiments, the solar cell further includes a first electrode arranged on the metal pattern region and electrically connected to the first doped conductive layer.
[0024] In some embodiments, the solar cell further includes a diffusion region, where the diffusion region is defined in the metal pattern region of the front surface of the substrate, a top of the diffusion region is in contact with the first tunneling layer, and the diffusion region has a greater doping element concentration than the substrate.
[0025] Accordingly, a photovoltaic module 1s further provided according to the embodiments of the present application, the photovoltaic module includes at least one cell string, where the at least one cell string is formed by connecting multiple solar cells, each of the multiple solar cells 1s the solar cell according to any one above, at least one package layer 3 configured to cover a surface of the at least one cell string, and at least one cover plate configured to cover a surface of the at least one package layer away from the at least one cell string.
[0026] The technical solutions provided according to the embodiments of the present application have at least the following advantages.
[0027] In the technical solutions of the solar cell provided according to the embodiments of the present application, the doping element concentration of the first doped conductive layer is set to be greater than that of the second doped conductive layer, that is, the first doped conductive layer is heavily doped compared with the second doped conductive layer, so that the sheet resistance of the first doped conductive layer is lower, and the contact recombination loss between the first doped conductive layer and a metal electrode is reduced. Moreover, the thickness of the first doped conductive layer is small, which can reduce the parasitic absorption of the first doped conductive layer to the incident light irradiated to the front surface of the substrate. The doping element concentration of the second doped conductive layer is small, on the one hand, which can not only reduce the Auger recombination of the second doped conductive layer, maintain the passivation performance of the second doped conductive layer, reduce the carrier recombination centers in the PN junction formed by the second doped conductive layer and the substrate, increase the carrier concentration, and improve the open- circuit voltage and short-circuit current. On the other hand, due to the large thickness of the second doped conductive layer, the risk of the doping elements of the second doped conductive layer diffusing into the substrate due to the thin second doped conductive layer can also be reduced, so as to avoid the problem that the doping elements of the second doped conductive layer accumulate at an interface of the substrate and form a "dead layer", thus improving the carrier transmission efficiency, and reducing the generation of carrier recombination centers.
[0028] One or more embodiments are described as examples with reference to the corresponding figures in the accompanying drawings, and the exemplary description does not constitute a limitation to the embodiments. The figures in the accompanying drawings do not constitute a proportion limitation unless otherwise stated.
[0029] FIG. 1 is a schematic structural view of a cross-section of a solar cell provided according to an embodiment of the present application;
[0030] FIG. 21s a curve graph shows that a doping concentration of a second doping element 4 changes with a doping depth;
[0031] FIG. 3 is a curve graph shows that a doping concentration of a first doping element changes with a doping depth;
[0032] FIG. 4 is a schematic structural view of a cross-section of another solar cell provided according to an embodiment of the present application; and
[0033] FIG. 5 is a schematic structural view of a photovoltaic module provided according to another embodiment of the present application.
[0034] It is known from the background technology that the photoelectric conversion efficiency of the solar cells in the prior art is low.
[0035] Itis found in the analysis that one of the reasons for the low photoelectric conversion efficiency of the solar cell in the prior art is that, first, at present, a diffusion process is generally used to convert a part of the substrate into an emitter at the front surface of the substrate. The emitter has different types of doping ions from the substrate, thus forming a PN junction with the substrate. However, this structure will lead to excessive carrier recombination in the metal pattern region of the front surface of the substrate, which will affect the open-circuit voltage and conversion efficiency of the solar cell. In addition, for the front surface and the rear surface of the solar cell, the reception of incident light is generally inconsistent. Therefore, the performance requirements for the doped conductive layer on the front surface of the solar cell and the doped conductive layer on the rear surface of the solar cell are inconsistent. However, in a solar cell of prior art, the doped conductive layer of the solar cell is generally not connected with the feature of being located on the front surface or the rear surface, resulting in being impossible to effectively improve the photoelectric conversion performance of the solar cell.
[0036] The embodiments of the present application provide a solar cell, in which the doping element concentration of the first doped conductive layer on the front surface of the substrate is set to be greater than that of the second doped conductive layer on the rear surface of the substrate, so that the sheet resistance of the first doped conductive layer is lower, thus reducing the contact recombination loss of the first doped conductive layer, which is beneficial to improve the carrier collection efficiency. Moreover, the thickness of the first doped conductive layer 1s small, which can reduce the parasitic absorption of the first doped conductive layer to the incident light irradiated to the front surface of the substrate. The doping element concentration of the second doped conductive layer is small, on the one hand, which can not 5 only reduce the Auger recombination of the second doped conductive layer, thus improving the passivation performance of the second doped conductive layer. On the other hand, due to the large thickness of the second doped conductive layer, the risk of the doping elements of the second doped conductive layer diffusing into the substrate due to the thin second doped conductive layer can also be reduced, so as to avoid the problem that the doping elements of the second doped conductive layer accumulate at an interface of the substrate and form a "dead layer", thus improving the transmission efficiency of carriers, and improving the photoelectric conversion efficiency of the solar cell.
[0037] The embodiments of the present application will be described in detail below with reference to the accompanying drawings. However, those skilled in the art may appreciate that, in the various embodiments of the present application, numerous technical details are set forth in order to provide the reader with a better understanding of the present application. However, the technical solutions claimed in the present application may be implemented without these technical details and various changes and modifications based on the following embodiments.
[0038] FIG. 1 is a schematic structural view of a cross-section of a solar cell provided according to an embodiment of the present application.
[0039] Referring to FIG. 1, the solar cell includes a substrate 100 having a front surface and a rear surface opposite to the front surface, a first tunneling layer 110 and a first doped conductive layer 120 arranged on a metal pattern region of the front surface of the substrate 100 and arranged in sequence in a direction away from the front surface of the substrate 100.
The first doped conductive layer 120 has a same type of doping elements as the substrate 100.
The solar cell further includes a second tunneling layer 140 and a second doped conductive layer 150 arranged on the rear surface of the substrate 100 and arranged in sequence in a direction away from the rear surface of the substrate 100. The second doped conductive layer 150 has different type of doping elements from the first doped conductive layer 120, the first doped conductive layer 120 has a greater activated doping element concentration than the second doped conductive layer 150, and a thickness d1 of the first doped conductive layer 120 is not greater than a thickness d2 of the second doped conductive layer 150.
[0040] It can be understood that the front surface of the substrate 100 receives more incident light than the rear surface of the substrate 100. In the embodiments of the present application, for the feature that the first doped conductive layer 120 is located on the front surface of the substrate 100 and receives more incident light on the front surface of the substrate 100. The doping element concentration of the first doped conductive layer 120 set to be big, and the 6 thickness of the first doped conductive layer 120 is set to be small. In this way, it can not only reduce the parasitic absorption of the first doped conductive layer 120 to the incident light, but also reduce the sheet resistance of the first doped conductive layer 120, thereby improving the metal contact recombination loss of the first doped conductive layer 120 and improving the carrier collection efficiency.
[0041] In view of the feature that the second doped conductive layer 150 is located on the rear surface of the substrate 100, and the second doped conductive layer 150 forms a rear PN junction with the substrate 100, the activated doping element concentration of the second doped conductive layer 150 is set to be small, which can reduce the Auger recombination of the second doped conductive layer 150, improve the passivation performance of the second doped conductive layer 150, thereby reducing the recombination of photogenerated carriers generated in the PN junction, improving the carrier concentration, and increasing the short circuit current and the open circuit voltage.
[0042] In addition, the thickness of the second doped conductive layer 150 is not greater than the thickness of the first doped conductive layer 120. Specifically, in some embodiments, the thickness of the first doped conductive layer 120 can be equal to the thickness of the second doped conductive layer 150. Since the activated doping elements concentration of the second doped conductive layer 150 is small, in the process of actually forming the second doped conductive layer 150, the doping elements will not accumulate too much in the second doped conductive layer, thus avoiding the formation of too many "dead layers".
[0043] In other embodiments, the thickness of the second doped conductive layer 150 is greater than the thickness of the first doped conductive layer 120. In this way, a longer doping path can be provided for the doping elements in the second doped conductive layer 150, which can reduce the generation of "dead layer" due to the accumulation of doping elements in the second doped conductive layer 150 at the interface of the substrate 100, and improve the mobility of photogenerated carriers. In addition, since the doping element concentration of the second doped conductive layer 150 is relatively low, the problem of doping elements being accumulated at the interface of the substrate 100 due to the high doping element concentration in the second doped conductive layer 150 can be further reduced.
[0044] The substrate 100 is configured to receive incident light and generate photogenerated carriers. In some embodiments, the substrate 100 is a silicon substrate, and material of the silicon substrate includes at least one of monocrystalline silicon, polycrystalline silicon, amorphous silicon or microcrystalline silicon. In other embodiments, the material of the 7 substrate 100 may also be silicon carbide, organic material or multi-component compound. The multi-component compound includes but are not limited to perovskite, gallium arsenide, cadmium telluride, copper indium diselenide, and other materials.
[0045] In some embodiments, there are doping elements in the substrate 100. The type of doping elements is N-type or P-type. The N-type elements can be group V elements such as phosphorus (P), bismuth (Br), antimony (Sb) or arsenic (As). The P-type elements can be group
III elements such as boron (B), aluminum (Al), gallium (Ga) or indium (In). For example, in response to the substrate 100 being a P-type substrate, there are P-type doping elements in the substrate 100. Alternatively, in response to the substrate 100 being a N-type substrate, there are N-type doping elements in the substrate 100.
[0046] The front surface and the rear surface of the substrate 100 are configured to receive incident light or reflected light. In some embodiments, the front surface of the substrate 100 is set as a pyramid textured surface, so that the reflectivity of the front surface of the substrate 100 to the incident light is small, and thus enhancing the absorption and utilization rate of light.
The rear surface of the substrate 100 is set as a non-pyramid textured surface, such as a stacked step shape, so that the second tunneling layer 140 located at the rear surface of the substrate 100 has a high density and uniformity, and the second tunneling layer 140 has a desirable passivation effect on the rear surface of the substrate 100.
[0047] The first tunneling layer 110 and the first doped conductive layer 120 arranged on the front surface of the substrate 100 form a passivation contact structure on the front surface of the substrate 100. The second tunneling layer 140 and the second doped conductive layer 150 on the rear surface of the substrate 100 form a passivation contact structure on the rear surface of the substrate 100. The passivation contact structure is set on both the front surface and the rear surface of the substrate 100, so that the solar cell becomes a double-sided tunnel oxide passivated contact (TOPCON) solar cell. In this way, the passivation contact structure on the front surface and the rear surface of the substrate 100 can reduce the carrier recombination on the front surface and the rear surface of the substrate 100. Compared with the passivation contact structure formed on only one of the front surface and the rear surface of the substrate 100, the carrier loss of the solar cell is greatly reduced, thus improving the open circuit voltage and the short circuit current of the solar cell. In the embodiments of the present application, the first tunneling layer 110 and the first doped conductive layer 120 are only arranged on the metal pattern region of the front surface of the substrate 100, so as to reduce the parasitic absorption of the first doped conductive layer 120 to the incident light and improve 8 the absorption and utilization rate of the non metal pattern region of the front surface of the substrate to the incident light.
[0048] By forming a passivation contact structure, the recombination of carriers on the surfaces of substrate 100 can be reduced, thus increasing the open-circuit voltage and improving the photoelectric conversion efficiency of the solar cell. In some embodiments, materials of the first tunneling layer 110 and the second tunneling layer 140 include dielectric material, such as silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon nitride, aluminum oxide or titanium oxide.
[0049] The first doped conductive layer 120 and the second doped conductive layer 150 are used to play a field passivation role. Specifically, the surface passivation effect is achieved by forming an internal electric field at the interface of the substrate 100 to reduce the concentration of electrons or holes at the interface of the substrate 100.
[0050] In the actual process of preparing the first doped conductive layer 120 and the second doped conductive layer 150, the diffusion process needs to be carried out in the first doped conductive layer 120 and the second doped conductive layer 150. In the actual diffusion process, the doping element concentration may be too high to exceed the maximum solid solubility of the first doped conductive layer 120, the second doped conductive layer 150 or the substrate 100, which will lead to the so-called "dead layer". The existence of the "dead layer" will cause lattice defects, resulting in the precipitation of some doping elements, which cannot be used as donor impurities, and will become the composite center due to lattice mismatch and dislocation, resulting in the low life of minority carriers.
[0051] Inthe embodiments of the present application, a second doped conductive layer 150 is arranged on the rear surface of the substrate 100, so that the area of the formed PN junction 1s large. In order to reduce the recombination of photo-generated carriers generated by the PN junction on the rear surface of the substrate 100 and improve the concentration of carriers, it is necessary to avoid the problem of "dead layer" at the interface of substrate 100 as much as possible, so as to prevent the problem of lattice defects caused by "dead layer" from becoming the recombination center. Based on this, the thickness of the second doped conductive layer 150 is set to be relatively large, which can provide a long doping path for the doping elements in the second doped conductive layer 150, thus improving the problem of "dead layer" caused by the accumulation of the doping elements in the second doped conductive layer 150 at the interface of the substrate 100, and improving the mobility of photogenerated carriers. In 9 addition, the doping element concentration in the second doped conductive layer 150 is set to be low, which can further improve the problem of forming accumulation at the interface of the substrate 100 due to the high doping element concentration of the second doped conductive layer 150.
[0052] Since the front surface of the substrate 100 receives more incident light, in order to reduce the absorption of incident light by the front surface of the substrate 100, the first doped conductive layer 120 is only arranged on the metal pattern region of the front surface of the substrate 100, which can reduce the parasitic absorption of the first doped conductive layer 120 to the incident light, so as to improve the carrier mobility of the rear surface of the substrate 100 while improving the utilization rate of the front surface of the substrate 100 to the incident light, and improving the photoelectric conversion performance of the solar cell. In some embodiments, the metal pattern region is defined as an electrode region.
[0053] In some embodiments, the thickness d1 of the first doped conductive layer 120 ranges from 20 nm to 300 nm, for example, it can be 20 nm to 50 nm, 50 nm to 80 nm, 80 nm to 130 nm, 130 nm to 150 nm, 130 nm to 180 nm, 180 nm to 230 nm, 230 nm to 260 nm, or 260 nm to 300 nm. In this range, the thickness of the first doped conductive layer 120 is small, which can further reduce the parasitic absorption of the first doped conductive layer 120 to the incident light and improve the utilization rate of the solar cell to the incident light. In addition, since the thickness of the first doped conductive layer 120 is small, the diffusion elements in the first doped conductive layer 120 are more concentrated after the diffusion process of the first doped conductive layer 120, which can improve the carrier concentration of the first doped conductive layer 120, thus lowering the sheet resistance of the first doped conductive layer 120, reducing the metal contact recombination loss of the first doped conductive layer 120, and improving the collection capacity of carriers. Moreover, in this range, the thickness of the first doped conductive layer 120 is not too small, which enables the first doped conductive layer 120 form a strong electrostatic field on the front surface of the substrate 100, and significantly improves the field passivation effect of the first doped conductive layer 120.
[0054] In some embodiments, the first doped conductive layer includes the first doping element. The first doping element is activated by annealing. The activation rate of the first doping element in the first doped conductive layer 120 ranges from 40% to 80%, for example, 40% to 45%, 45% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75% or 75% to 80%. In some embodiments, the activation rate can be obtained by dividing the concentration of activated doping elements by the total concentration of injected doping 10 elements. Doping elements can only work after being activated, and inactive doping elements will form a "dead layer". The activation rate of the first doping element is related to the thickness of the first doped conductive layer 120 and the concentration of the total injected doping elements in the first doped conductive layer 120. Based on the thickness of the first doped conductive layer 120 ranging from 20 nm to 300 nm, the activation rate of the first doping element in the first doped conductive layer 120 is set to be from 40% to 80%, so that the concentration distribution of the activated first doping elements in the first doped conductive layer 120 in the thickness direction of the first doped conductive layer 120 is in line with the expectation. The first doped conductive layer 120 has a low sheet resistance while the first doped conductive layer 120 having a desirable field passivation effect on the substrate 100.
Thus, the carrier recombination on the front surface of substrate 100 can be reduced.
[0055] Specifically, in some embodiments, in the direction from the first doped conductive layer 120 to the substrate 100, the concentration of the activated first doping element in the first doped conductive layer 120 gradually decreases, that is, a concentration gradient pointing to the substrate 100 is formed in the first doped conductive layer 120, which is conducive to the formation of an electrostatic field pointing to the substrate 100 on the front surface of the substrate 100 by the first doped conductive layer 120, thus improving the carrier concentration on the front surface of the substrate 100 to achieve surface passivation.
[0056] In some embodiments, the concentration of the activated first doping element ranges from 1x10*°atom/cm’ to 6x10*%atom/cm?, for example, 1x10*atom/cm’ to 2x10 atom/cm’, 2x10%atom/cm® to 3x102%atom/cm’, 3x10*°atom/cm® to 4x 10%%atom/cm}?, 4+ 10*atom/cm’ to 5x10*atom/cm’ or 5x10?%atom/cm’ to 6 10%%atom/cm). In this range, the concentration of the activated first doping element in the first doped conductive layer 120 is relatively high. On the one hand, the first doped conductive layer 120 can form a strong electrostatic field on the front surface of the substrate 100, which is conducive to enhancing the field passivation effect of the first doped conductive layer 120. On the other hand, in this range, the sheet resistance of the first doped conductive layer 120 can be reduced, which is beneficial to reduce the metal contact recombination loss of the first doped conductive layer 120, thus improving the carrier collection efficiency. On the other hand, in this range, the concentration of the first doping element activated in the first doped conductive layer 120 will not be excessive, so that the concentration of the first doping element injected in the first doped conductive layer 120 will not be excessive during the actual formation of the first doped conductive layer 120, which can prevent the activation rate of the first doping element from decreasing due to the high 11 concentration of the first doping element injected, resulting in a high probability of forming a "dead layer". Moreover, the concentration of the activated first doping element is not excessive, which can also prevent the problem that the concentration of doping elements in the first doped conductive layer 120 is excessive, resulting in the strong Auger recombination of the first doped conductive layer 120, and maintain the desirable passivation performance of the first doped conductive layer 120.
[0057] In some embodiments, the ratio of the width of the first doped conductive layer 120 to the width of the substrate 100 ranges from 0.0001 to 0.0012, for example, 0.0001 to 0.0002, 0.0002 to 0.0004, 0.0004 to 0.0006, 0.0006 to 0.0008, 0.0008 to 0.0010 or 0.0010 to 0.0012.
The first doped conductive layer 120 is arranged in the metal pattern region of the front surface of the substrate. In this range, the width of the first doped conductive layer 120 is much smaller than that of the substrate 100, thus greatly reducing the parasitic absorption of the first doped conductive layer 120 to the incident light, thus greatly improving the utilization rate of the substrate 100 to the incident light. In addition, in this range, the width of the first doped conductive layer 120 is not too small compared with the substrate 100, and the Fermi energy level difference can be formed between the first doped conductive layer 120 and the substrate 100, so as to form an energy band bend in the metal pattern region of the front surface of the substrate 100, which can effectively block the passage of minority carriers without affecting the transmission of majority carriers, thus realizing the selective collection of carriers, further enhancing the collection capacity of carriers. Based on this, in some embodiments, the width of the first doped conductive layer can be ranged from 20pm to 200um. For example, it can be 20pm to 40um, 40pm to 65um, 65um to 85um, 85um to 100um, 1004m to 130um, 130pm to 150pm, 150pum to 180um or 180um to 200pm.
[0058] In some embodiments, the area ratio of the first doped conductive layer to the front surface of the substrate 100 ranges from 0.01 to 0.15. The area ratio of the first doped conductive layer 120 to the front surface of the substrate 100 here refers to a ratio of the total area of the first doped conductive layer 120 to the front surface of the substrate 100 in all metal pattern regions to the area of the substrate 100. In this range, the first doped conductive layer 120 is not only ensured to have a desirable field passivation effect, but also the parasitic absorption of the first doped conductive layer 120 to the incident light irradiated on the front of the substrate 100 is reduced.
[0059] In some embodiments, the thickness d2 of the second doped conductive layer 150 ranges from 50 nm to 500 nm, for example, it can be 50 nm to 100 nm, 100 nm to 150 nm, 150 12 nm to 200 nm, 200 nm to 250 nm, 250 nm to 300 nm, 350 nm to 400 nm, 400 nm to 450 nm or 450 nm to 500 nm. In addition, in this range, the thickness d2 of the second doped conductive layer 150 is larger than that of the first doped conductive layer 120, which can ensure that in the actual process of forming the second doped conductive layer 150. A longer diffusion path is provided for the doping elements, and the accumulation of the doping elements in the second doped conductive layer 150 is prevented, which reduces the probability of forming a “dead layer”, reduces the recombination probability of carriers, increases the number and efficiency of photogenerated carriers generated by the second doped conductive layer 150 to transmit into the substrate 100, thus increasing the open-circuit voltage and the short-circuit current. In addition, in this range, the thickness of the second doped conductive layer 150 will not be excessive, so as to prevent the problem that the thickness of the second doped conductive layer 150 is too large and cause greater stress on the substrate 100, which ensures that the substrate 100 has desirable stability.
[0060] In some embodiments, the second doped conductive layer 150 includes the second doping element, which is activated by annealing. It can be understood that the thickness d2 of the second doped conductive layer 150 is large, thus providing a long diffusion path for the second doping element. Therefore, even if the concentration of the second doping element is low, the diffusion of the second doping element in the second doped conductive layer 150 is more uniform and dispersed, which reduces the risk of the second doping element accumulating inthe second doped conductive layer 150. Thus, the actual annealing yield of the second doping element is improved, the forming of “dead layer” is reduced, and the activation rate of the second doping element in the second doped conductive layer 150 is improved. Specifically, in some embodiments, the activation rate of the second doping element in the second doped conductive layer 150 ranges from 30% to 80%, for example, 30% to 35%, 35% to 40%, 40% to 50%, 50% to 55%, 55% to 60%, 60% to 65%, 65% to 70%, 70% to 75% or 75% to 80%.
[0061] In some embodiments, the activated second doping element concentration is 4 X 1019atom/cm3 to 9 X 1019atom/cm3, for example, 4 X 1019atom/cm3 to 5 X 1019atom/cm3 5 X 1019atom/cm3 to 6 X 1019atom/cm3. 6 X 1019atom/cm3 to 7 X 1019atom/cm3. 7
X 1019atom/cm3 to 8 X 1019atom/cm3 or 8 X 1019atom/cm3 to 9 X 1019atom/cm3. In this range, the concentration of the activated second doping element in the second doped conductive layer 150 will not be too high, so that the Auger recombination of the second conductive layer can be reduced, and the carrier recombination on the back of the substrate 100 can be reduced, so that the mobility of the carrier generated by the second doped conductive layer 150 can be 13 improved to the substrate 100. In addition, in this range, during the actual formation of the second doped conductive layer 150, the concentration of the second doping element injected into the second doped conductive layer 150 is also low, which can prevent the formation of accumulation in the second doped conductive layer 150 due to the high concentration of the injected second doping element from increasing the probability of forming a “dead layer”, and further improve the mobility of carriers.
[0062] Referring to FIG. 2, in some embodiments, the second doped conductive layer 150 includes: the first region and the second region. The second region is defined close to the substrate 100. In the direction from the first region to the second region, the slope of the doping curve of the activated second doping element in the first region is not less than 0, and the slope of the doping curve of the activated second doping element in the second region is less than 0.
The slope of the doping curve is a slope of the curve that the doping concentration of the activated second doping element changes with the doping depth. In some embodiments, the doping curve of the concentration of the activated second doping element and the total injected second doping element with the doping depth can be measured by the electrochemical capacitance-voltage (ECV) method and the secondary ion mass spectrometry (SIMS) method.
Tag 1 represents the doping curve of the total injected second doping element concentration changing with the doping depth, and tag 2 represents the doping curve of the activated second doping element concentration changing with the doping depth.
[0063] The slope of the doping curve of the activated second doping element in the first region is not less than 0, for example, it can be equal to 0 or greater than 0. That is to say, in the first region, with the increase of doping depth, the doping concentration of the activated second doping element gradually increases or remains unchanged, that is, the doping concentration of the activated second doping element remains at a high level. Specifically, in some embodiments, in the first region, the slope of the doping curve of the activated second doping element in the first region is equal to 0, that is, with the increase of the doping depth, the doping concentration of the activated second doping element remains unchanged. In other embodiments, in the first region, the slope of the doping curve of the activated second doping element in the first region is greater than 0, that is, with the increase of the doping depth, the doping concentration of the activated second doping element gradually increases. In other embodiments, in the first region, the slope of the doping curve of the activated second doping element in the first region can also be greater than 0 and then equal to 0, that is, with the increase of the doping depth, the doping concentration of the activated second doping element first 14 increases gradually, and then remains unchanged.
[0064] In addition, tt is not difficult to find from FIG. 2 that the concentration of the total injected second doping element in the first region shows the same trend as the concentration of the activated second doping element with the increase of the doping depth, that is, the concentration of the total injected second doping element in the first region also remains at a higher concentration level. This shows that the activation rate of the second doping element remains high in the first region.
[0065] In the second region, the slope of the doping curve of the activated second doping element in the first region is less than 0, that is, the concentration of the activated second doping element gradually decreases with the increase of the doping depth, and the concentration of the total injected second doping element in the second region gradually decreases with the increase of the doping depth. In addition, it is not difficult to find that in the second region, with the increase of doping depth, the concentration difference between the activated second doping element and the total injected second doping element gradually increases, which indicates that inthe second region, with the increase of doping depth, the activation rate of the second doping element gradually decreases. This is because, with the increase of the diffusion depth of the second doping element, the problem of accumulation in the second doped conductive layer 150 is gradually serious, which will lead to the generation of a “dead layer”, thus reducing the activation rate of the second doping element.
[0066] Specifically, at a junction between the first region and the second region, the activation rate of the second doping element starts to decrease, indicating that the “dead layer” problem starts to appear at the junction between the first region and the second region.
Referring to FIG. 2, the doping depth at the junction between the first region and the second region is approximately 130 nm.
[0067] Although the problem of “dead layer” still exists in the second doped conductive layer 150, in the embodiments of the present application, by setting the thickness d2 of the second doped conductive layer 150 to be large and the concentration of active doping elements in the second doped conductive layer 150 to be low, the concentration and the thickness of the dead layer can be reduced, thus improving the problem of “dead layer”. For details, reference is made to FIG. 3, which shows a curve of the doping concentration of the first doping element changing with the doping depth.
[0068] In the embodiments of the present application, the thickness of the second doped conductive layer 150 is set to be greater than the thickness of the first doped conductive layer 15
120, and the activated doping element concentration of the second doped conductive layer 150 is set to be less than the activated doping element concentration of the first doped conductive layer 120. Therefore, comparing the first doped conductive layer 120 with the second doped conductive layer 150, from FIG. 3, it is not difficult to find that in response to the doping depth of the first doped conductive layer 120 being approximately 100 nm, the activation rate of the first doping element begins to decline significantly, that is, the “dead layer” begins to appear.
Referring to Figure 3, in response to the doping depth of the second doped conductive layer 150 being approximately about 130 nm, the activation rate of the second doping element begins to decline. It can be seen that the formation of the “dead layer” is closely related to the thickness of the doped conductive layer. By setting the thickness of the second doped conductive layer 150 to be larger, it can provide a longer diffusion path for the second doping element, thus reducing the “dead layer” problem.
[0069] In some embodiments, the slope of the doping curve of the activated second doping element in the first region is greater than 0, and the slope of the active second doping element in the first region ranges from 1xE!° to 1xE", for example, can be 1xE!® to 52E, 5xE to 1xE'7, 1<E" to 5xE, SxEF to IxE!8 1xE" to 57E! or 5xE!3 to 1<E". In this range, the doping concentration of the second doping element in the first region is higher, thus maintaining a higher activation rate of the second doping element. The second doped conductive layer 150 in the first region mainly plays a major role in generating a large Fermi energy level difference with the substrate 100, thus forming an energy band bend at the rear surface of the substrate 100, effectively blocking the passage of minority carriers, and realizing the selective transmission of carriers. In addition, the slope of the doping curve of the activated second doping element in the second region ranges from -1*E!° to -1=E°°, for example, it may be -1<E' to -5xEl6, -5xE!6 to -1=EV, -IxEV to -SxE!7, -5xE! to -1*E"™, -1xE" to -
SEB, -SxE¥to-1xEY., -1:E1 to -5xEP or -1xE" to -1xE2°. In this range, the slope of the doping curve of the activated second doping element in the second region is not too small compared with that in the first region, so that the doping concentration of the second doping element in the second region does not fall too fast, which can reduce the volume of the “dead layer” in the second doped conductive layer 150, reduce the lattice defects of the second doped conductive layer 150, thus reducing the recombination of photogenerated carriers and increasing carrier concentration.
[0070] In some embodiments, the concentration of the activated second doping element in the first region ranges from 4x10Yatom/cm® to 9x10" atom/cm®, for example, it may be 16
4x10%atom/cm’ to 5x10atom/cm’, 5-10" atom/cm® to 6x 102atom/em’, 6x 10!%atom/cm) to 7x10" atom/cm?, 7x 10"atom/cm’ to 810" atom/cm® or 8x10"atom/cm® to 9x10" atom/cm?>.
The concentration of the activated second doping element in the second region ranges from 1x10%atom/cm® to 9x10"atom/cm’, for example, it may be Ixl0latom/cm? to 5x10"atom/cm’, 5x10!%atom/em? to 1x107atom/cm’, 1x107atom/cm’® to 5x10'7atom/cm’, 5x10"atom/cm? to 1x10"%atom/cm?, 1x10%atom/cm® to 1x10"atom/cm® or 1x10" atom/cm? to 9x10"atom/cm’. In this range, the concentration of the first doping element and the second doping element activated in the first doped conductive layer 120 is smaller than that of the first doping element activated in the first doped conductive layer 120, which can reduce the Auger recombination of the second doped conductive layer 150 and the recombination of photogenerated carriers. Moreover, in this range, the concentration of activated second doping elements in the first and second regions is not too small, which can ensure that the rear PN junction formed by the second doped conductive layer 150 and the substrate 100 can produce more photogenerated carriers, and ensure that the solar cell has better photoelectric conversion performance.
[0071] Since the activation rate of the second doping element in the second doped conductive layer 150 in the first region is high, that is, the probability of forming “dead layer” is low, so it is necessary to set the thickness of the first region to be large, so as to reduce the “dead layer” problem. Based on this, in some embodiments, the thickness of the second doped conductive layer 150 in the first region is set to be 50 nm to 500 nm, for example, it can be 50 nm to 86 nm, 80 nm to 120 nm, 120 nm to 180 nm, 180 nm to 250 nm, 250 nm to 300 nm, 300 nm to 350 nm, 350 nm to 400 nm or 400 nm to 500 nm, and the thickness of the second doped conductive layer 150 in the second region is 30 nm to 300 nm, for example, it can be 30 nm to 50 nm, 50 nm to 80 nm, 80 nm to 130 nm, 130 nm to 170 nm to 220 nm, 220 nm to 250 nm 250nm to 270nm or 270nm to 300nm. In this range, the thickness of the second doped conductive layer 150 in the first region is large, which can reduce the volume of the “dead layer” in the second doped conductive layer 150, thus reducing the lattice defects of the second doped conductive layer 150. It is worth noting that in some embodiments, regardless of the thickness of the first and second doped conductive layer 150, the total thickness range of the second doped conductive layer 150 composed of the first and second regions is kept in the range of 50nm to 500nm, so that the stress of the second doped conductive layer 150 on the substrate remains small.
[0072] In some embodiments, the substrate 100 is an N-type substrate, the first doped 17 conductive layer 120 is an N-type doped conductive layer, and the second doped conductive layer 150 is a P-type doped conductive layer.
[0073] In other embodiments, the substrate 100 is a P-type silicon substrate, the first doped conductive layer 120 is a P-type doped conductive layer, and the second doped conductive layer 150 is an N-type doped conductive layer.
[0074] In some embodiments, in response to the substrate 100 being an N-type substrate, the first doped conductive layer 120 being an N-type doped conductive layer, and the second doped conductive layer 150 being a P-type doped conductive layer, the doping element of the first doped conductive layer is set to be phosphorus, and the doping element of the second doped conductive layer 150 is set to be boron.
[0075] In some embodiments, the materials of the first doped conductive layer and the second doped conductive layer 150 include at least one of amorphous silicon, microcrystalline silicon or polycrystalline silicon.
[0076] In some embodiments, the solar cell further includes: the first passivation layer 170.
A first part of the first passivation layer 170 is located on a surface of the first doped conductive layer 120 away from the substrate 100, and a second part of the first passivation layer 170 is located on the non metal pattern region of the front surface of the substrate. The first passivation layer 170 can play a good passivation effect on the front surface of the substrate 100, for example, it can perform a good chemical passivation on the hanging bonds on the front surface ofthe substrate 100, reduce the density of defect states on the front surface of the substrate 100, and better inhibit the carrier recombination on the front surface of the substrate 100. The first part of the first passivation layer 170 is in direct contact with the front surface of the substrate 100, so that there is no first tunneling layer 110 and the first doped conductive layer 120 between the first passivation layer 170 of the first part and the substrate 100, which can reduce the parasitic absorption of the first doped conductive layer 120 to the incident light.
[0077] In some embodiments, the top surface of the first part of the first passivation layer 170 is not flush with the top surface of the second part of the first passivation layer 170.
Specifically, the top surface of the first part of the first passivation layer 170 can be lower than the top surface of the second part of the first passivation layer 170, so that the thickness of the first part on the front surface of the substrate 100 is not excessive, and the stress damage on the front surface of the substrate 100 caused by the excessive thickness of the first part can be prevented, so that the front surface of the substrate 100 will produce more interface state defects, resulting in more carrier recombination centers. 18
[0078] In some embodiments, the first passivation layer 170 may be a single-layer structure, and in other embodiments, the first passivation layer 170 may also be a multi-layer structure.
In some embodiments, material of the first passivation layer 170 may be at least one of silicon oxide, aluminum oxide, silicon nitride or silicon nitride.
[0079] In some embodiments, the solar cell further includes: the first electrode 160, which is arranged on the metal pattern region and electrically connected to the first doped conductive layer 120. The PN junction formed on the rear surface of the substrate 100 is used to receive the incident light and generate the photogenerated carriers. The photogenerated carriers are transmitted from the substrate 100 to the first doped conductive layer 120, and then to the first electrode 160, which is used to collect the photogenerated carriers. Since the type of doping ions of the first doped conductive layer 120 is the same as that of the substrate 100, the metal contact recombination loss between the first electrode 160 and the first doped conductive layer 120 is reduced, the current-carrying contact recombination between the first electrode 160 and the first doped conductive layer 120 can be reduced, and the short-circuit current and the photoelectric conversion performance of the solar cell can be improved. In some embodiments, the first electrode 160 is arranged on the metal pattern region of the front surface of the substrate 100. The first electrode 160 penetrates the first passivation layer 170 to be in electrical contact with the first doped conductive layer 120.
[0080] Referring to FIG. 4, in some embodiments, the solar cell further includes a diffusion region 130. The diffusion region 130 is located in the metal pattern region of the substrate 100.
The top of the diffusion region 130 is in contact with the first tunneling layer 110. The doping element concentration of the diffusion region 130 is greater than that of the substrate 100.
[0081] The diffusion region 130 can be used as a carrier transmission channel. The diffusion region 130 is only formed in the metal pattern region of the substrate 100, so that the carriers in the substrate 100 can be easily transferred to the doped conductive layer through the diffusion region 130, that is, the diffusion region 130 acts as a carrier transmission channel.
Moreover, since the diffusion region 130 is only formed in the metal pattern region of the substrate 100, the carriers in the substrate 100 can be centrally transmitted to the diffusion region 130, and then transmitted to the first doped conductive layer 120 through the diffusion region 130, thus greatly improving the carrier concentration in the first doped conductive layer 120. It is noteworthy that in the embodiments of the present application, the diffusion region 130 1s not formed in the non metal pattern region of the substrate 100, so that the carrier concentration on the non metal pattern region of the front surface of the substrate 100 is not 19 excessive, which prevents the problem of serious carrier recombination on the non metal pattern region of the front surface of the substrate 100. In addition, it can also prevent the carriers in the substrate 100 from being transmitted to the non metal pattern region of the front surface of the substrate 100, thus avoiding the accumulation of carriers on the non metal pattern region of the front surface of the substrate 100. The formation of a “dead layer” on the non metal pattern region of the front surface of the substrate 100 is prevented, which prevents the problem of excessive carrier recombination, thus improving the photoelectric conversion performance of the solar cell as a whole.
[0082] In some embodiments, the solar cell further includes a second passivation layer 180, which is located on a surface of the second doped conductive layer 150 away from the substrate 100. The second passivation layer 180 is configured to play a good passivation effect on the rear surface of the substrate 100, reduce the density of defect states on the rear surface of the substrate 100, and better inhibit the carrier recombination on the rear surface of the substrate 100. Since a protrusion on the rear surface of the substrate 100 has a small degree of convexity, the second passivation layer 180 arranged on the rear surface of the substrate 100 has higher flatness, which can improve the passivation performance of the second passivation layer 180.
[0083] In some embodiments, the second passivation layer 180 may be a single-layer structure, and in other embodiments, the second passivation layer 180 may also be a multi- layer structure. In some embodiments, material of the second passivation layer 180 may be at least one of silicon oxide, aluminum oxide, silicon nitride or silicon nitride.
[0084] In some embodiments, the solar cell further includes: the second electrode 190, which is located on the back of the substrate 100, and the back electrode penetrates the second passivation layer 180 to be in electrical contact with the second doped conductive layer 150.
[0085] In the solar cell provided according to the above embodiments, the doping element concentration of the first doped conductive layer 120 on the front surface of the substrate 100 is set to be greater than that of the second doped conductive layer 150 on the rear surface of the substrate 100, so that the sheet resistance of the first doped conductive layer 120 is lower, thus reducing the contact recombination loss of the first doped conductive layer 120, which is beneficial to improve the carrier collection efficiency. Moreover, the thickness of the first doped conductive layer 120 is small, which can reduce the parasitic absorption of the first doped conductive layer 120 to the incident light irradiated to the front surface of the substrate 100. The doping element concentration of the second doped conductive layer 150 is small, on the one hand, which can not only reduce the Auger recombination of the second doped 20 conductive layer 150, thus improving the passivation performance of the second doped conductive layer 150. On the other hand, due to the large thickness of the second doped conductive layer 150, the risk of the doping elements of the second doped conductive layer 150 diffusing into the substrate 100 due to the thin second doped conductive layer 150 can also be reduced, so as to avoid the problem that the doping elements of the second doped conductive layer 150 accumulate at an interface of the substrate 100 and form a "dead layer", thus improving the transmission efficiency of carriers, and improving the photoelectric conversion efficiency of the solar cell.
[0086] Accordingly, a photovoltaic module is further provided according to another aspect of the embodiments of the present application. Referring to FIG. 5, the photovoltaic module includes: at least one cell string, where the at least one cell string is formed by connecting multiple solar cells 101, each of the multiple solar cells 101 is the solar cell 101 according to any one of above embodiments. The photovoltaic module further includes at least one package layer 102 configured to cover a surface of the at least one cell string, and at least one cover plate 103 configured to cover a surface of the at least one package layer 102 away from the at least one cell string. The solar cell 101 is electrically connected to form multiple cell strings in the form of whole or multiple pieces, and the multiple cell strings are electrically connected in series and/or parallel.
[0087] Specifically, in some embodiments, the multiple cell strings can be electrically connected by a conductive strip 104. The at least one package layer 102 is configured to cover the front surface and the rear surface of the solar cell 101. Specifically, the at least one package layer 102 can be an organic package film such as ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film or polyethylene terephthalate (PET) film. In some embodiments, the at least one cover plate 103 may be a glass cover plate, a plastic cover plate and other cover plates with light transmission function. Specifically, the surface of the at least one cover plate 103 towards the at least one package layer 102 may be provided with protrusions and recesses, thus increasing the utilization rate of incident light.
[0088] Although the present application is disclosed above with preferred embodiments, it is not used to limit the claims. Any person skilled in the art can make some possible changes and modifications without departing from the concept of the present application. The scope of protection shall be subject to the scope defined by the claims of the present application.
[0089] Those of ordinary skill in the art can understand that the above embodiments are specific examples for realizing the present application, and in actual applications, various 21 changes may be made in form and details without departing from the scope of the present application.
Any person skilled in the art can make their own changes and modifications without departing from the scope of the present application.
Therefore, the protection scope of the present application should be subject to the scope defined by the claims.
22
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CN202211098149.9A CN117673178A (en) | 2022-09-08 | 2022-09-08 | Solar cell and photovoltaic module |
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DE (1) | DE202023101750U1 (en) |
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